Safety shut-off device

ABSTRACT

A safety shut-off device for sections of fluid circuits, which in case of damage or the like, have to shut off from each other on safety considerations. The safety shut-off device includes at least two valves connected to each other via a control chamber. A first pressure differential with the control chamber closes the valves and a second pressure differential, which is greater than the first, opens the valves.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional application of U.S. application Ser.No. 10/911,852, filed Aug. 5, 2004, now U.S. Pat. No. 7,165,569, whichis herein incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of Invention

The invention relates to a safety shut-off device for sections of fluidcircuits that, in case of damage or the like, have to be shut off fromeach other on safety considerations.

2. Related Technology

Such safety shut-off devices are provided in order to shut off singlesections of, for example, refrigerant or hydraulic circuits in case ofdamage and to prevent the fluid contained in the circuits fromcompletely flowing out. This ensures that the outflow of fluids (whichare relevant considering safety, cost-intensive and hazardous for theenvironment or health) from a damaged circuit is limited.

It is known in the state-of-the-art to be anxious to shut off variouscircuit sections, for example refrigerant circuits. The peculiar problemis the fact that the refrigerants are substances that are hazardous forthe environment or, due to enrichment of refrigerants in the areas beingair-conditioned, are hazardous to the persons in these areas. This isparticularly relevant for refrigerant plants in motor vehicles where, incase of damage, the passengers could be confronted with the refrigerantin a very small space.

U.S. Pat. No. 5,918,475 proposes, in case of damage of vehicle airconditioning units, to close, for example, the air exit of the airconditioning unit into the passenger compartment in order to prevent orreduce the entry of refrigerant into the passenger compartment.Following this strategy, however, does not avoid the loss of refrigerantfrom the system; only the entry of refrigerant into the passengercompartment will be reduced.

A particular disadvantage is that, in the case of damage, it cannot beensured that no other leaks or connections to the passenger compartmentdeveloped, which would allow the refrigerant to flow into the passengercell.

The solution, in the case of damage to only single parts or sections ofthe refrigerant plant that has been know for long and is described inthe state-of-the-art. One possibility is that an externally controlledvalve is closed in a de-energized condition and therefore shuts off theevaporator exit. Another possibility is to provide non-return valves inorder to prevent any unintentional exit of the refrigerant due to backflowing of the refrigerant into sections affected by the damage.

According to the teachings of U.S. Pat. No. 5,983,657 it is proposed(for a vehicle air conditioning unit) to use a combination of anelectromagnetic valve and anon-return valve to prevent the refrigerantfrom flowing out of the evaporator when the compressor is not operating.The decompression valve is used as the electromagnetic valve.

A disadvantage of the described state-of-the-art, particularly if thedecompression valve is used as a shut-off valve, is that thedecompression valve is limited in its true function due to the addedsealing function. Further, a decompression device extended by such anadditional function is more cost-intensive because of the highercomplexity of the structure.

This invention is therefore aimed at the establishment of a safetyshut-off device that undertakes the shut-off of sections or line loopsof a fluid circuit without an expensive control.

SUMMARY OF THE INVENTION

The problem mentioned above is solved by a safety shut-off device that,in one embodiment, includes two chambers with connections for thesections that are to be shut off from each other. The chambers have twoconnections each and are separated from each other by a piston. One ofthe connections for each chamber is closed by a closing element with asealing force element, this occurring when both chambers have the samepressure. Further, two actuating devices are provided so as to befunctionally connection to the closing elements and the piston. When thepiston is moved due to a pressure difference between the connections,the closing element in the chamber with the higher pressure thereforeopens the associated connection so that fluid can flow from a sectionwith higher pressure into the other section with lower pressure. Theaccompanying pressure increase in the section with the previously lowerpressure ensures that the corresponding closing element of the chamberwith the lower pressure is overcome by the fluid against the pressure ofthe sealing force element so that the fluid is capable to circulate inboth sections.

Alternatively, the problem of the invention is solved by a safetyshut-off device that has at least two segmenting valves which areconnected to a control chamber at low pressure. The segmenting valvehave stepped pistons that, held by a sealing force element, close asealing taper connection. Further, an annular chamber connection isprovided in the body of the segmenting valve and through which the fluid(after having overcome the sealing force element) flows from a firstsegmenting valve from a section to be shut off of the fluid circuit intoanother section to be shut off and eventually into the second segmentingvalve. Through the sealing taper connection for the second segmentingvalve, the fluid flows to the annular chamber connection back into theadjacent section to be shut off of the fluid circuit. According to theinvention, the control chamber has the lowest system pressure, wherebyfluid can only flow in the segmenting valve if there is a pressuredifference between the pressure at the annular chamber connection or thesealing taper connection, and the pressure in the control chamber. Inaddition, a non-return valve is provided that enables pressure balancingbetween the control chamber and the annular chamber connection when thepressure in the control chamber is too high.

According to a preferred embodiment of the invention the stepped pistonhas an elastomer coating with a sealing lip, with the sealing lipfunctioning as non-return valve. When the stepped piston is closed thefluid, after having overcome the sealing lip, flows from the controlchamber to the annular chamber connection. In this embodiment thestepped piston is provided in the body so as to create an annular gap topas the fluid from the section of the control chamber over the sealinglip to the sealing taper connection. The sealing lip thus functions as anon-return valve.

Preferably a number N of segmenting valves are provided for a safetyshut-off device, whereby N sections are capable of being shut off fromeach other.

According to the concept of the invention, the safety shut-off device isa passive one, which on pressure balance shuts off at least two sectionsfrom each other or separates, respectively, one section from theremainder of the fluid circuit. It is particularly advantageous that incase of damage, without any auxiliary energy added, further afterflow oroutflow, respectively, of fluid into or out of, respectively, a sectionof the fluid circuit is prevented.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional details, features and advantages of the invention will becomeapparent from the subsequent description of exemplary embodiments takenin conjunction with the accompanying drawings of which shows:

FIG. 1 safety shut-off device, schematic sectional view;

FIG. 2 refrigeration plant with safety shut-off device, principalcircuit diagram;

FIG. 3 combined heat pump/air conditioning unit with safety shut-offdevice;

FIG. 4 segmenting valve with integral non-return valve;

FIG. 5. segmenting valve with elastomeric sealing lip as non-returnvalve;

FIG. 6 partial view of a segmenting valve with sealing lip;

FIG. 7. segmenting valve block in an application with three sections tobe shut off.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a safety shut-off device 17 with two chambers 19, 20.Connections 8, 9 and 6, 7 for the sections to be shut off from eachother 10, 21 are arranged at the chambers. The chambers 19, 20 areseparated from each other by a piston 1. One connection 8, 9 in eachcase in the chambers 20, 19 is closed by closing elements 3 with sealingforce elements 18. If the chamber 19, 20 have the same pressure, theclosing elements 3 tightly close the connections 8, 9 by means of thesealing force elements 18. In this position no fluid can circulatebetween the section 10 and the section 21.

In case of damage in section 10, only the fluid contained there canexit, the fluid contained in section 21 cannot pass to the outside overthe section 10, because it is prevented from entering into the section10 by the closing elements 3.

The closing elements are provided with two actuating devices 2 that arefunctionally connected to the closing elements 3 and the piston 1 sothat when the piston 1 is moved due to a pressure difference in thechambers 19, 20 or at the connections 6, 7, the closing element 3 in thechamber with the higher pressure opens the associated connection so thatthe fluid can flow from the section 21 into the section 10. The pressureincrease accompanying the flowing in of the fluid results in that thecorresponding closing element 3 is overcome by the fluid against thesealing force element 18 so that the fluid can flow into the section 21.According to the preferred embodiment of the invention the sealing forceelements 18 are designed as springs.

According to another advantageous embodiment of the safety shut-offdevice 17 of the invention, the movement of the piston 1 is limited bylimiting elements 4. In this case the actuating devices 2 are guided inthe interior of the piston 1 by a guide 22 with a stop 23. When thepiston 1 is displaced, the actuating devices 2 are taken along by thestop 23 in direction of pressure propagation so that the closing element3 opens the respective connection 8 or 9 for the fluid.

Preferably the safety shut-off device 17 is designed symmetric, wherebyon pressure balance in the chambers 19 and 20, the piston 1 is in acentral position.

In FIG. 2, a refrigerant circuit according to the invention isschematically shown, in which a safety shut-off device 17 is provided.Here the section to be shut off 10 is the inner heat exchanger of an airconditioning unit, or the evaporator, respectively.

The operations of the refrigerant circuit is as follows: A compressor 11compresses refrigerant vapor, which is cooled, or liquefied,respectively, in the gas cooler/condenser 37 at high pressure. Therefrigerant passes at high pressure through the connection socket 7 intothe chamber 20 of the safety shut-off device 17. Because of the highpressure, the piston 1 is moved to the left and the actuating device 2is taken along by the stop 23. The closing element 3 opens theconnection socket 8, the refrigerant can flow to the decompressionelement 12 and then to the evaporator 10. Thus, the refrigerant is atthe connection socket 9 of the safety shut-off device 17 at lowpressure. Through a pressure build-up by the applied refrigerant theclosing element 3 is displaced against the force of the sealing forceelement 18 so that the refrigerant flows into the chamber 19 and to theconnection socket 6 and then to the refrigerant collector 15 and finallyto the compressor 11.

A particular advantage of the use of the safety shut-off device 17according to the invention is that, based on its symmetric design, thesafety shut-off device 17 is not only suitable for the air conditioningdesign of a refrigerant circuit, but also for the combined airconditioning unit-heat pump operation as shown in FIG. 3. In such aconstruction, it is particularly advantageous that the piston 1 ispositioned depending on the pressure application of the chambers 19, 20by the fluid at the connections 6 and 7, whereby the plant automaticallyand passively adapts itself to the operational mode by a change of theoperational mode without any specific control being needed at the safetyshut-off device 17.

In FIG. 3 a combined air conditioning unit/heat pump is shown in aprincipal circuit diagram. It should be noted that because of thesymmetry, the safety shut-off device 17 can be used for sections, orline loops, respectively, with changing direction in the flow of thefluid. In heat pump mode, the multi-way valve 13 is oriented so that therefrigerant flows in contrast to the function described according toFIG. 2, from the compressor to the connection socket 6 and through thechamber 19 to the connection socket 9 and, thus in opposite direction offlow through the heat exchanger 10 now operating as condenser/gas coolerto the decompression element 12. Over a refrigerant/coolant heatexchanger 16, operating as evaporator, the refrigerant is then passedvia the multi-way valve 14 to the refrigerant collector 15 andcompressor 11. In the air conditioning mode, multi-way valve 13 passesthe refrigerant from the compressor 11 to the gas/cooler condenser 37and multi-way valve 14 passes the refrigerant from chamber 19 to therefrigerant collector 15.

FIG. 4 shows a segmenting valve 32, for use as an alternate embodimentof the invention, with an integrated non-return valve 33. A controlchamber 25, an annular chamber connection 26 and a sealing taperconnection 27 are made in the body 24. The fluid can enter through theannular chamber connection 26 or the sealing taper connection 27. Astepped piston 28 is held by a sealing force element 18 in such a waythat the stepped piston 28 closes the sealing taper connection 27. Inthis closed position of the stepped piston 28, all three connections 26,27 and 25 are shut off from each other. When in a section 21 to be shutoff of a fluid circuit, for example, at the annular chamber connection26 or the sealing taper connection 27, a fluid is at high pressure, thestepped piston 28 is displaced against the force of the sealing element18 and fluid flows over the cylinder ring in the body 24, with the ringdesigned to be an annular channel 35 in the lower portion, from one tothe other connection 26, 27, respectively.

If a fluid of the section 10 of a fluid circuit is at high pressure atthe annular chamber connection 26, the fluid flows after opening of theflow path by the stepped piston 28, as described above, over the annularchannel 35 to the sealing taper connection 27 and hence passes from thesection 10 to the section 21 to be shut off. In the representationaccording to FIG. 4 a non-return valve 33 is arranged between thecontrol chamber 25 and the annular chamber connection 26.

If there is a higher pressure in the control chamber 25 compared withthe section 10 of the fluid circuit, this pressure is relieved over thenon-return valve 33 to the annular chamber connection 26. The segmentingvalve 32 with the mechanical non-return valve 33 permits fluid flow onlywhen and is opened in this sense, if either a fluid flow at highpressure in contrast to the pressure in the control chamber 25 opens thestepped piston 28 against the force of the sealing force element 18, orif the pressure in the control chamber 25 there is a pressure that issignificantly higher than the lowest system pressure and this higherfluid pressure relieves over the non-return valve 33 to the annularchamber connection 26.

In FIG. 5 a segmenting valve with elastomer sealing lip 30 as non-returnvalve 33 is shown is a preferred embodiment of the invention. Analogousto the representation in FIG. 4, the control chamber 25, the annularchamber connection 26 and the sealing taper connection 27 are arrangedin the body 24. According to the shown advantageous embodiment of theinvention, the stepped piston 28 is provided with an elastomer coating29. It is a particular advantage that the elastomer coating 29 at thesealing flanks 34 of the body, under the condition of small pressuredifferences, seals the section of the annular chamber connection 26 fromthe section of the sealing taper connection 27.

According to a particularly preferred embodiment of the invention theelastomer coating 29 at its ends is adopted to form a sealing lip 30.The sealing lip 30 with its limiting end bears against the body 24 suchthat, under high pressure application over the annular chamberconnection 26 or the sealing taper connection 27, the sealing lip 30 ispressed against the body 24 and seals the annular channel 35 against theannular channel 36 and the control chamber 25, whereby the fluid at highpressure can pass from the annular chamber connection 26 to the sealingtaper connection 27, after due to the pressure difference in the annularchannel 35 relative to the pressure in the control chamber 25, thestepped piston 28 displaced in direction of the control chamber 25.

According to the invention the control chamber 25 is always connectedwith the lowest pressure predominant in the system. The sealing lip 30,according to this preferred embodiment, additionally functions asnon-return valve to provide for a pressure balance in case of higherpressure in the control chamber 25 compared to the annular channel 35 sothat afterwards, in the control chamber 25, therein also the lowerpressure of the annular channel 35. Fluid flow from the annular channel35 into the control chamber 25 is without appreciable mass flow only dueto the pressure balancing within the fluid circuit over a deliberate andadmitted leakage past the sealing lip 30 through the annular gap 36 intothe control chamber 25.

The control chamber 25 of this preferred embodiment of the invention hasonly a minimum volume for the use in a refrigerant circuit and isdesigned as dead volume without mass flow function and does notcontribute to the refrigerant transport. The control chamber 25essentially serves as reference of the low pressure for the realizationof the segmenting function of the segmenting valve 32 according to theinvention.

A particular advantage of this embodiment is that by the provision of anelastomer coating 29 and a sealing lip 30, two functions can beproduction-economically implemented in a segmenting valve 32. First, theelastomer coating 29 on the stepped piston 28 seals the sections to beshut off from each other at the sealing flanks 34 without expensivemachining of the inner surfaces of the body 24 and the outer surface ofthe stepped piston 28, respectively. Second, the elastomer coating 29designed as sealing lip 30 at the ends performs the function of anon-return valve 33.

A spring functions as a sealing force element 18, whereby the controlstates and necessary pressure differences for the segmenting valve 32can be controlled through the dimensioning of the spring.

According to this embodiment of the invention, the concept is realizedto shut off in case of damage also several lines, or line loops,respectively. This is achieved by that three pressures are compared bythe segmenting valve 32-the pressures at the annular chamber connection26, sealing taper connection 27 and control chamber 25. The connectionof a plurality of segmenting valves 32 to the safety shut-off device 31over the control chamber 25 enables to establish a number N of sectionto be shut off from each other corresponding to the number N ofsegmenting valves 32.

As in the case of damage, the pressure difference in fluid systems levelout very quickly, the sections to be shut off from each other aresecurely separated by the sealing force elements 18 and their action onthe stepped piston 28, and the outflow of fluid from the sections of thefluid circuit not directly affected by the damage is effectivelyavoided.

FIG. 6 is an enlarged representation of the preferred embodiment of thecontrol piston with elastomer coating 29 and sealing lip 30. The steppedpiston 28 is in its upper part surrounded by any elastomer coating 29,at the end of which a sealing lip 30 is made or formed, respectively.The sealing lip 30 closes the annular gap 36 such that a fluid underhigh pressure can flow into the annular channel 35 through the annularchamber connection 26 and flow off to the sealing taper connection 27.The sealing lip 30 prevents the fluid from flowing to the controlchamber 25. It is particularly advantageous that this allows to achievethat the body 24 with the cylinder designed in it needs no manufacture-and cost-intensive treatment due to the sealing function of theelastomer.

FIG. 7 presents an embodiment according to the invention of a safetyshut-ff device 31 consisting of three segmenting valves 32 as it isused, for example, in a refrigerant circuit of a combined airconditioning unit/heat pump of a motor vehicle, whereby in the casepresented, an additional inner heat exchanger 38 is provided in additionto the evaporator 10. The control chamber 25 connects all threesegmenting valves 32 a, 32 b and 32 c to each other.

At the annular chamber connection 26 of the segmenting valve 32 a, inheat pump mode, there is fluid at high pressure in the section 21, whichflows over the sealing taper connection 27 into the section 10 with theevaporators to be shut off in case of damage. In air conditioning modethe refrigerant flows to the sealing taper connection 27 of thesegmenting valve 32 b and eventually to the compressor 11 over therefrigerant collector 15.

In heat pump mode the refrigerant passes through the annular chamberconnection 26 of the segmenting valve 32 c to the sealing taperconnection 27 and through the decompression element 12 and theadditional inner heat exchanger 38 to the sealing taper connection 27 ofthe segmenting valve 32 a.

According to another embodiment of the invention the safety shut-offdevice can also be advantageously used for hydraulic systems.

1. A safety shut-off device for sections of fluid circuits comprising atleast two segmenting valves each with an annular chamber connection, asealing taper connection and a control chamber at low pressure areprovided, the control chambers of the segmenting valves are connected toeach other and that in each segmenting valve a stepped piston isprovided and held by a sealing force element, a first pressuredifference between the annular chamber connection or the sealing taperconnection compared to the pressure in the control chamber closes thesealing taper connection, a second pressure difference being greaterthan the first pressure difference opens the sealing taper connectionsuch that fluid can flow from the annular chamber connection to thesealing taper connection or vice versa, a non-return valve is providedover which a higher pressure in the control chamber compared with thepressure in the annular chamber connection can be relieved.
 2. Thesafety shut-off device of claim 1 wherein the non-return valve iscreated by an elastomer coating on the stepped piston, which functionsas non-return valve and allows the fluid to flow only for a closedstepped piston from the control chamber to the sealing taper connection,whereby an annular gap between the body and the stepped piston isprovided.
 3. The safety shut-off device of claim 1 wherein a number N ofsegmenting valves are provided in the safety shut-off device and exactlyN sections are capable of being shut off from each other.
 4. The safetyshut-off device of claim 1 wherein the sealing force elements aresprings.
 5. The safety shut-off device of claim 1 provided in arefrigerant circuit to prevent the outflow of refrigerant in case ofdamage.
 6. The safety shut-off device of claim 5 wherein sections of therefrigerant circuit to be shut off contain inner heat exchangers of anair conditioning unit or heat pump or a combined air conditioningunit/heat pump.
 7. The safety shut-off device of claim 1 provided in ahydraulic circuit to segment sections thereof and prevent the outflow ofrefrigerant in case of damage.